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Raised sodium level in my blood

I had a blood test to check for arthritis. It came back negative but my GP said that it showed I had a raised level of sodium. He has requested a further blood test to see if it has changed. What does this mean and what is the impact?

1 March 2021

Your body carefully balances the sodium levels in the blood. The normal range for sodium levels in the blood is 135-145 millimoles per litre (mmol/L). Some people naturally have slightly high sodium levels, usually around 146-148 mmol/L.

A low level of sodium in the blood (also known as hyponatremia) is relatively common. A high level of sodium in the blood, i.e. 146 mmol/L or above (hypernatremia) is much less common.

If you’re otherwise feeling well, it’s quite possible the test result was due to  poor sample collection or a reflection of your sodium level on that day, and the next reading may be normal. But higher levels of sodium in the blood that don’t come down, do need further investigation.


Symptoms and causes of hyponatremia

Low sodium levels in the blood causes hyponatremia. This usually happens if you drink too much water in a short time.

The most common symptoms are:

  • Nausea
  • Vomiting
  • Headaches.

In really serious instances, low sodium levels can cause the brain to swell leading to confusion, fits, comas and sometimes death, though this is rare.

Treating hyponatremia

Treatment for hyponatremia will depend on the underlying cause and may be as simple as adjusting your diet, drinking less water or stopping taking certain medications until sodium levels are restored. In more extreme cases a saline (salt) solution may be administered intravenously to gradually raise sodium levels to a safe level.


Symptoms and causes of hypernatremia

Hypernatremia is defined as a serum sodium level above 146 mmol/L.

Hypernatremia can be caused by:

  • Dehydration, from diarrhoea and vomiting or diuretics (usually water tablets given for high blood pressure)
  • Kidney problems
  • A rare condition called diabetes insipidus, which affects the body’s ability to process water. This is a much less likely cause.

Symptoms of high sodium levels in the blood can include:

  • Thirst
  • Headache
  • Nausea and vomiting
  • Lethargy
  • Confusion
  • Seizures
  • Loss of consciousness/coma.

Treatment for hypernatremia

There are a number of ways to reduce sodium levels in your blood. These include staying hydrated, reducing your salt intake and exercising. You’ll find lots of information and help with all of these in the Healthy lifestyle pages on our website.

Answered by the Health at Hand nurses.  

Sources and further reading

Dehydration – Know your risk – AXA Health

Getting your salt intake right – AXA Health

Diet and nutrition centre - AXA Health

Useful resources

World Action on Salt 2021. (Acessed 01 March 2021)

Food Switch 2021. (Assessed 01 March 2021)

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